Further work on the cellular mechanisms underlying neurologic and pscyhiatric disorders is limited by the fact that neurons throughout the brain utilize common mechanisms for critical functions such as synaptic plasticity, whereas specific neural systems are affected in different disorders. A large part of the Laboratory is now working with the Gene Expression Nervous System Atlas (GENSAT) project ( funded by NINDS and NIMH ) to produce transgenic mice with Cre-recombinase under the regulation of promoters to drive expression in specific neuron populations. Our part of this work is to characterize the expression of Cre in the brains of such transgenic lines and to provide such lines to the Mutant Mouse Regional Resource Center (MMRRC) for distribution to the research community ( Gong et al., 2007). In the past year we characterized 100 Cre driver lines of which 25 were added to those made available through the GENSAT project: http://www.gensat.org/index.html .